1. Field of the Invention
The present invention relates to inspection method and an inspection device, repairing method and a repairing device for an organic electroluminescence (EL) panel having processes for inspecting an organic EL element or a pixel of an organic EL panel made of the organic EL element.
2. Description of the Related Art
In recent years, an organic EL panel made of organic EL elements having characteristics, such as a low-voltage driving function, spontaneous light emission, and a high-speed response, has been used as a display device.
As shown in FIG. 14, the organic EL element has a structure in which an anode 100 placed on a glass substrate 400, a cathode 200 placed so as to face the anode 100, and an organic EL layer 300 sandwiched between the anode 100 and the cathode 200. Moreover, a color filter 500 is used in some cases so as to improve a color developing property as a display.
The gap between the anode 100 and the cathode 200 is about 1 μm, which forms a very fine structure. Consequently, during manufacturing processes of an organic EL display device, a portion having an inhomogeneous film thickness in the organic EL layer 300 tends to occur due to inhomogeneousness in the thickness of the metal electrodes or a foreign matter 399 mingled between the electrodes. Since a portion having a thin film thickness in the organic EL layer 300 has low electric resistance, the holes 110 and the electrons 210 are positively supplied thereto to cause a leakage current, with the result that the light emission of the organic EL layer 300 becomes non-uniform to cause an inhomogeneously emitting pixel.
Moreover, in the case where the anode 100 and the cathode 200 completely conduct to each other due to, for example, a large foreign matter mingled therein, since no combinations occur between the holes 110 and the electrons 210, no light emission is generated in the organic EL layer 300 to cause a non-lighting pixel (hereinafter, referred to as a “dark point”). In the case where there are many non-uniform light emission pixels and dark points in the display device, since the image quality and display quality deteriorate extremely, satisfactory products cannot be delivered.
For this reason, it is necessary to detect the non-uniform light emission pixels and dark points by inspection and to repair these. As the repairing method, for example, methods have been proposed in which weak leakage light, generated upon application of a reverse bias voltage to the organic EL device, is detected so that the metal electrodes on the periphery thereof are burned and cut off.
Referring to FIGS. 15A, 15B, and 15C, the following description will discuss a detecting process in which such weak leakage light is detected through color filters. FIG. 15 is an explanatory view showing a state of a leakage light emission of an organic EL panel with color filters of red, green and blue (pixel portions of red, green and blue are shown in this order from the left) are installed therein.
In FIG. 15, when explained by exemplifying a red filter pixel, upon applying a reverse bias voltage to the anode 101 and the cathode 201 on the glass substrate 401 by a power supply 901, a leakage light emission 701 is generated from a current leakage generation portion 601, and a leakage light emission 801 passed through a red color filter 501 is detected by a weak light detection camera 1000 through a lens 1100.
FIG. 16 shows an example of a state of leakage light that has passed through a color filter.
The following explanation relating to FIG. 16 is given on the assumption that the structure shown in FIG. 15 is used, and in this state, it is supposed that a leakage light emission (red filter pixel) 701, a leakage light emission (green filter pixel) 702, and a leakage light emission (blue filter pixel) 703, shown in FIG. 15, have completely the same spectrum and completely the same intensity, and that the red color filter 501, the green color filter 502, and the blue color filter 503 have the same transmittance in the infrared wavelength region, with the transmittances in the visible region being reduced in the order of the red color filter 501, the green color filter 502, and the blue color filter 503.
In this case, the total amounts of light emission become smaller in the order of leakage light emission (visible to infrared wavelength regions) 804 passed through the red color filter 501, leakage light emission (visible to infrared wavelength regions) 805 passed through the green color filter 502, and leakage light emission (visible to infrared wavelength regions) 806 passed through the blue color filter 503; however, an amount of leakage light emission 807 passed through the red color filter 501 (infrared wavelength region), an amount of leakage light emission 808 passed through the green color filter 502 (infrared wavelength region), and an amount of leakage light emission 809 passed through the blue color filter 503 (infrared wavelength region) have the same quantity of light. Here, the rates of the amounts in which infrared components are contained in the leakage light 801 passed through the red color filter 501, the leakage light 802 passed through the green color filter 502, and the leakage light 803 passed through the blue color filter 503 become relatively different from one another.
Consequently, in the case where the lens 1100 in FIG. 15 has such a specification as to cause deviations in focal points between the visible and near-infrared regions, even if distances from the weak light detection camera 1000 to a current leakage generation position (red filter pixel) 601, a current leakage generation position (green filter pixel) 602, and a current leakage generation position (blue filter pixel) 603 are all the same, the focal point positions become different among the leakage light 801 passed through the red color filter 501, the leakage light 802 passed through the green color filter 502 and the leakage light 803 passed through the blue color filter 503.
However, in the above-mentioned conventional technique, since light transmitting characteristics are different depending on the red color filter, green color filter and blue color filter, the intensities and focal points differ depending on the types of color filters, with the result that it becomes difficult to carry out a high-speed inspecting operation at one time, and it is also difficult to determine references of the area and intensity for each of the types of color filters.